The present invention relates to a semiconductor device and a method of manufacturing the same, and particularly to a method of forming a multilayered conductive layer for a semiconductor device, which improves electromigration resistance.
A conventional multilayered conductive layer configuration employed in a semiconductor device is generally illustrated as a sectional structure shown in FIG. 6. An aluminum (Al) film 14 as a conductive layer is used, and a titanium (Ti) film 12 and a titanium nitride (TiN) film 13 provided on the Ti film 12 are used as a barrier layer 16 on an insulator layer 11 deposited on an integrated circuit 10, so as to avoid a conductive layer-to-layer leak developed by diffusion of Al thereof into an insulating film. Now, the Ti film is effective in improving the quality of an Al film, principally, its orientation, and an improvement in the orientation of the Al film provides the effect of enhancing electromigration resistance. This electromigration (EM) is a phenomenon in which atoms are moved by the flow of a current. Since it produces a failure such as breaking of a conductive layer, an improvement in EM resistance is essential to the enhancement of reliability. Further, the TiN film 13 is needed to prevent the reaction of the Ti film and the Al film for the wired metal.
Next, the Al film 14 used as the wired metal is deposited by heating at 200xc2x0 C. to 400xc2x0 C. The reason why heating is made upon the formation of the Al film, is to make an Al grain large by heating to enhance the EM resistance and to improve step coverage (state of a film deposited on a step) in a contact hole. The migration has been considered to take place along a grain boundary. Since the grain boundary is reduced if the Al grain is relatively set larger than a conductive layer width, the electromigration (EM) can be restrained.
Thereafter, Ti, TiN, or a laminated layer of Ti and TiN, for example is deposited as an antireflection film (ARM) 15 relative to an Al surface based on a photolithography process. Further, the so-deposited film is subjected to a photolithography process and an etching process and then to patterning, whereby each of conductive layers is formed.
In the above method on the other hand, since the Al film 14 is deposited at the high temperature of from 200xc2x0 C. to 400xc2x0 C. upon deposition thereof after the formation of the TiN film 13, nitrogen gas (N2 gas) is released from the surface of the TiN film 13 and from within the TiN film 13 to within an Al deposition chamber, so that N2 is brought into the Al film 14. It has generally been known that the mixing of N2 gas upon Al deposition interferes with the growth of a grain and hence EM resistance is degraded. Thus, the present method had a problem that reliability was degraded.
The present invention has been made in view of the above problem involved in the conventional semiconductor device and semiconductor device manufacturing method, particularly, the method of forming the multilayered conductive layer for the semiconductor device. It is an object of the present invention to provide a novel and improved semiconductor device and a method of manufacturing the semiconductor device, which are capable of preventing N2 from being captured during the deposition of a conductive layer Al film and enhancing electromigration resistance.
The present invention provides a method of manufacturing a semiconductor device, comprising, forming an insulator layer on an integrated circuit, forming a barrier layer comprised of a first titanium film and a titanium nitride film on the insulator layer, heat-treating the barrier layer to release nitrogen gas from the titanium nitride film, forming a second titanium film on the barrier layer, and forming an aluminum film used as a wired metal on the second titanium film.